Program Information

Modification of An Anthropomorphic Phantom to Accommodate OSL Dosimeters

K Ogden*, M Roskopf, SUNY Upstate Medical Univ, Syracuse, NY

SU-E-I-61 Sunday 3:00PM - 6:00PM Room: Exhibit Hall

Purpose: To modify an anthropomorphic (Rando) phantom designed for use with TLD dosimeter chips to accept OSL dosimeters.

Methods: An adult male anthropomorphic phantom (Alderson Rando) has arrays of 5mm holes in each phantom slice that are designed to accept TLD dosimeter chips. Current OSL dosimeters are available in a small, 1 cm x 1 cm form factor that is convenient for external use clinically, but will not fit into the 5mm holes in Rando. The first (top) ten slices of an adult male Rando phantom (head and neck) were modified by machining 2mm slots 1.2 cm wide x 1.7 cm deep centered over the existing holes to allow placement of OSL dosimeters. Placing the slots coincident with the existing holes minimizes the amount of material removed from the phantom.

Results: Each modified hole in the phantom required the removal of approximately 0.25 cm^3 of phantom material. The use of OSL dosimeters has greatly simplified the measurement process and reduced the total time required to load, unload, and read the dosimeters. For the head and neck, a total time of approximately 4 hours is required for loading, scanning, unloading, and reading OSL chips. With TLD dosimeters, the time for the equivalent data collection was 10-12 hours.

Conclusion: Total time for dosimetry measurements using TLD chips in Rando is significant due to the care required in handling TLDs, as well as the time required for the anneal and read processes. Modification of the Rando phantom has greatly increased the efficiency of making in-phantom dose measurements. The total material removed from the phantom to accommodate the OSL dosimeters is less than 1% of the total material and so should have a negligible impact on overall phantom attenuation.